Siloxane compositions which cure through hydrosilylation reaction have the advantage that curing proceeds quickly to the deep interior without forming by-products. Because of this advantage, siloxane compositions are used in a variety of applications, for example, as molded rubber, adhesives, potting compounds for electric and electronic parts, and release coatings for paper and film.
Methods for the crosslinking of polysilanes are under consideration. For example, Robert West et al. reported that a composition comprising a polysilane having hydrogen as side chain substituents and trivinylphenylsilane can be cured through hydrosilylation catalyzed by chloroplatinic acid. This system, however, suffers from the problems that the side chain substituents are less reactive and that polysilane chains are cleaved by the chloroplatinic acid catalyst and further oxidized.
Robert West, Journal of Organometallic Chemistry, vol. 300, pp. 327-346, 1986, also reports that a polysilane having alkenyl groups in side chains, alone or in combination with a polyfunctional unsaturated compound, can be cured through photo-crosslinking reaction. However, the crosslinked film cannot retain the properties of polysilane because this method utilizes cleavage of polysilane chains.
With respect to the technique of bonding a Si--H group-bearing compound to an alkenyl group-bearing compound through hydrosilylation, various examples are disclosed in JP-A 201933/1987 corresponding to U.S. Pat. No. 4,639,501. This method relates to a method for preparing pre-ceramic organopolymers, but not to a technique of forming crosslinked films. It is not indicated whether a tough, solvent-insoluble film can be formed by this method. Similarly, no allyl alcohol esters are disclosed as examples of the alkenyl compounds subject to hydrosilylation.
The crosslinking of polysilanes through hydrosilylation is disclosed in many other patents, for example, JP-A 311728/1992, 32899/1993, 59176/1993, and 310946/1993. None of these methods, however, indicate the use of allyl alcohol esters as the crosslinking agent.